Dhaunayne Aundae leads the Aundae Clan from her remote lair, a tomb called Ashmelech. To locate it, head to middle of the northern coast of the mainland. There is a medium sized island directly north of you  not the one Dagon Fel is on and not the one Ald Redaynia is on. It is a small nondescript island of small to medium size.

Dhaunayne is at the bottom of the Ashmelech tomb. Explore your conversation options until she talks "about my family," which will trigger her first quest, which has two parts.

Find Vilandon

Go to the Sadrith Mora Mages Guild in Wolverine Hall and speak to Tusamircil. He will refer you to Sinyaramen, and give you a potion to deliver to Sinyaramen so that he will talk to you. Tusamricil does not know where Sinyaramen might be, but if you talk to Iniel (right there in the Mages Guild), she'll tell you to go to the Gateway Inn. Sinyaramen is on the second floor of the Inn. Follow your dialogue options to find out that a vampire named Kjeld killed Vilandon. Report back to Dhaunayne to begin the second phase of this quest, which is, not surprisingly:

Kill Kjeld

Kjeld is a Quarra vampire in Druscashti's upper level. He's behind a trapped door. After you find him and kill him, you can go back to Dhaunayne to receive your reward: access to the services of Mororurg and Gladroon, the Aundae clan merchants.

For your second quest, talk to Dhaunayne about the "vampire hunter." Dhaunayne wants you to (go ahead  guess ):

Kill Ano Vando

This vampire hunter's name is Ano Vando, and he's in Ald'ruhn. He'll be the guy in the iron armor with the magical ebony shield pacing back and forth near the Mages Guild. Now, the catch is this: you have to kill him in daylight with witnesses  try midday with some guards around. Also, Ano's got a special vampire-hunting shield, the Darksun Shield, and a vampire hunting mace, Light of Day, which will make him good at hurting you. Undaunted, you kill him anyway.

Don't equip his mace or shield while you're a vampire. Bad things will happen. Keep em if you like and head back to Dhaunayne. For your efforts you get the Aundae Amulet, which will recall you to headquarters when you equip it. Your last quest, as I mentioned previously, is going to be the same for all clans:

Kill 12 Berne and/or Quarra Vampires

Ask about "future rewards" to get this quest. It doesn't matter how many of which clan you kill, and you don't need any trophy to prove it  the game will keep track for you.

After you've visited the other vampire clan lairs and killed 12 vampires, zip back to HQ with your handy-dandy amulet and receive your final reward: access to the lair's cattle  you can feed off of them with your Vampire Touch, but don't kill them or you'll lose the privilege of using them.